Snapchat has just rejected an offer made by Facebook. But what makes it so popular that Mark Zuckerberg wants to buy it? The fleeting nature of the pleasure it provides.

Three thousand million dollars. First, try to digest this figure, and then think about the fact that it is the amount that Facebook offered in an attempt to buy out Snapchat, an offer Snapchat subsequently rejected.

What is Snapchat? A social network with no income, scant presence outside the US, whose key attraction lies in the fact that if you use it to send photos they automatically self-destruct a few seconds later. You take a photo, scribble down something along with it, decorate it or whatever, decide how long you want it to be visible (between one and ten seconds), and then you send it. The recipient has those few seconds to see it, during which time they have to keep two buttons pressed (an attempt to prevent them from doing a screen shot). After that time, the photo vanishes.

Last September some 26 million users sent over 350 million photos using Snapchat. But the real underlying reason for Facebook’s offer, is that a high percentage of the youth segment stopped using the all powerful Facebook when they started using Snapchat among themselves.

What is so special about Snapchat for it to attract so many users between the ages of 15 and 25 years? The simple answer is that Facebook is now used too widely, to the extent that their parent can now snoop on what they are getting up to, or even – horror of horrors – actually comment on it. But also, more than anything else, it is that fact that Snapchat does not remain on the network. It is deliciously ephemeral. Once it has fulfilled its communicative purpose, it disappears, end of story.

Deeply concerned about the force of this tool, Facebook tried to clone it - Facebook Poke is virtually identical to Snapchat - but even that didn’t work. Next move? Try to buy it. Let’s see where all this leads to.